I probably can't use all three of these mechanics at common. I just like the idea of creatures and enchantments being interchangeable.

I love Elektrik's wording for Become. I also think adding 2 to the CMC for the Become cost makes a good deal of sense.

Become Lightning - 2R
Enchantment - Aura
Enchant Creature
Enchanted creature gets +2/+0 and has first strike.
Become 3RR (3RR: Reveal cards from the top of your library until you reveal a creature with converted mana cost less than 5. Put it onto the battlefield enchanted by this, then shuffle your library.).

Become Angry 1R
Enchantment - Aura
Enchant Creature
Enchanted creature gets +2/+2 and must attack each turn if able.
Become 2RR (2RR: Reveal cards from the top of your library until you reveal a creature with converted mana cost less than 4. Put it onto the battlefield enchanted by this, then shuffle your library.)

Each Elemental you control can't be blocked except by two or more creatures.
Each enchanted creature you control can't be blocked except by two or more creatures.

Inner Fire - 1R
Enchantment
Morph - R (You may cast this face down as a 2/2 creature for 3. Turn it face up any time for its morph cost.)
Sacrifice ~: ~ deals 3 damage to target creature or player.

Unstable Elements - 2R
Enchantment
Morph - 2R (You may cast this face down as a 2/2 creature for 3. Turn it face up any time for its morph cost.).
Whenever an enchantment or an Elemental creature is put into the graveyard from the battlefield, ~ deals 1 damage to each opponent.

I would try increasing the difference in CMC and Become cost for cards like Become Lightning. Unlike cascade, you can get better base effects by setting the search restriction (CMC) and cost to become separately.

Become Angry 2R
Enchantment - Aura
Enchant Creature
Enchanted creature gets +2/+2 and has haste.
Become 3RR (3RR: Reveal cards from the top of your library until you reveal a creature card that costs less. Put it onto the battlefield enchanted by this, then shuffle your library.)

Also, with this wording I was just barely able to keep it to four lines of text in MSE.